The abuse of controlled substances in the United States and other parts of the world has reached epidemic proportions. To address this human tragedy significant administrative and technical resources are currently being expended to identify and implement technologies which deter, inhibit or prevent the unintentional, illicit, illegal and/or recreational use of controlled substances. Within the context of this discussion controlled substances are those identified by the US Drug Enforcement Administration (DEA) and as context of discussion herein may dictate, the controlled substance may either be the active pharmaceutical ingredient (as its free base or salt) or the formulated drug product. Further, the controlled substances of interest to this invention are the opioid narcotics—that is, the alkaloids derived from opium either by isolation from natural sources, semi-synthetic derivatives prepared by transformation of the natural isolates, synthetic acquisition and combinations thereof. A useful overview is “Opium and Its Alkaloids” found in the American Journal of Pharmaceutical Education, Vol. 66, Summer 2002, pp. 186-194.
The detrimental practice of drug abuse, particularly of oxycodone, the active ingredient in OxyContin®, is well recognized. Indeed, in December 2003 the General Accounting Office (GAO) issued a report to Congressional requesters entitled “Prescription Drugs, OxyContin Abuse and Diversion and Efforts to Address the Problem”. The document contains a statistical assessment indicating the severity of the abuse problem, the employment of marketing practices contrary to FDA regulations, the actions taken by Purdue Pharma, Federal and State Agencies tasked to prevent abuse and diversion of Oxycontin® while recognizing the legitimate medical necessity of the opioid narcotics to treat pain. Like many governmental reports, the GAO's assessment was thorough and presented a factual basis to the problem of Oxycontin® abuse. However, the report contained a “Recommendation for Executive Action” which essentially returned the problem to the FDA as indicated by the following excerpted paragraph.
“To improve the efforts to prevent or identify the abuse and diversion of schedule II controlled substances, we recommend that the Commissioner of Food and Drugs ensure that FDA's risk management plan guidance encourages pharmaceutical manufactures that submit new drug application for these substances to include plans that contain a strategy for monitoring the use of these drugs and identifying potential abuses and diversion problems.”
Indeed, the FDA has several “Guidance for Industry” documents, namely: 1) Development and Use of Risk Minimization Action Plans, 2) Pre-marketing Risk Assessment, and e) Good Pharmacovigilance Practices and Pharmacoepidemiologic Assessment. In the first cited Guidance the following excerpt is particularly poignant to this discussion:
“Opiate drug products have important benefits in alleviating pain but are associated with significant risk of overdose, abuse, and addiction. The Agency recommends that sponsors of Schedule II controlled substances, including Schedule II extended release or high concentration opiate drug products, consider developing RiskMAPS for these products.” [Note: RiskMAPS=risk minimization action plans.]
These Guidances, while well intended, employ administrative measures in an attempt to prevent drug abuse. As an example, the FDA recommends the RiskMAP to be designed according to the following criteria: 1) compatible with current technology, 2) applicable to both outpatient and inpatient use, 3) accessible to patients in diverse locales, including non-urban settings, and 4) consistent with existing tools and programs, or systems that have been shown to be effective with similar products, indications, or risks.
Again, the abuse of controlled substances in the United States has reached epidemic proportions which has yielded a significant economic burden on society and has seriously impacted the general health condition of the nation's society. While the origin of the abuse may be accredited to the irresponsible behavior of the abuser, the detrimental effects to society remain. For more than twenty-five years, the actions by the federal and state governments have had no apparent impact on the drug abuse crisis and the problem has escalated faster than the population's growth rate. Similarly, educational programs and intervention by the medical community have had limited effect. Indeed, those individuals who on their own initiative or through the assistance of family or friends who have sought help through drug addiction treatment programs have also responded poorly. In fact, the behavioral and/or physiological change needed to eliminate their abuse/dependence on controlled substances is usually only temporary. This is especially evident when you consider the rising epidemic in methadone abuse with the frequent occurrence of such abuse leading to death of the “patient”; i.e. even the treatment is leading to death.
In the context of public health, controlled substances fulfill medical necessities and will be required to treat legitimate ailments in both controlled environments (clinics, hospitals, alternate care sites) as well as in unmonitored circumstances (drug administration by the patient). Medical professionals, alert to the potential for drug abuse and diversion, attempt to restrict the use of various drugs particularly pain relief medications such as Oxycontin®. Unfortunately, this approach is inconsistent and may deny relief to patients truly suffering from pain. To the medical practitioner, the decision to prescribe, or not to prescribe, pain medication is agonizing and may be accompanied by legal liability. In regard to non-prescription drug products, the “decision” to restrict availability of pseudoephedrine containing products by requiring the pharmacy to stock and track these products from “behind-the-counter” also impedes the legitimate use of these products and places an undue burden on the pharmacist and the consumer. Of course, this action was taken in an effort to stem the trade of these products for their use in illicit methamphetamine production.
An additional burden is placed on the medical practitioner as drug abuse continues to escalate and is not limited to the abuse of “traditional” illegal/recreational drugs of previous generations but abuse practices have now broadened to include legitimate prescription drugs. A full-page advertisement was sponsored by eleven professional medical organizations in the Feb. 10, 2008 edition of The New York Times page A7 indicating that “teens abuse prescription drugs more than any illicit street drug except marijuana”. The advertisement further extols “prescription drugs are the drugs of choice for 12 and 13 year olds” and that “every day, 2500 kids age 12 to 17 try a painkiller for the first time”. Simply stated, teens are raiding the family medicine cabinet to get high. In fact, The Wall Street Journal Online of Mar. 25, 2008 reported in an article by Elizabeth Bernstein entitled “New Addiction on Campus: Raiding the Medicine Cabinet”, the increased prevalence of 18-25 years olds abusing prescription narcotics primarily due to their ready availability. In January 2008, the Office of National Drug Control Policy, under the authority of the Executive Office of the President, published “Prescription for Danger, A Report on the Troubling Trend of Prescription and Over-the-Counter Drug Abuse Among the Nation's Teens”. This report summarizes the crisis well and adds additional insight to the problem. For instance, “teens are abusing prescription drugs because many believe the myth that these drugs provide a “safe” high and they are easily available”. Statistically, it would appear parenting skills are ineffective and may only have limited influence on preventing a teen from abusing drugs.
Government initiatives to curb drug abuse, the heightened awareness among medical professionals for observing symptoms of drug abuse or for recognizing the potential for such abuse, and parental guidance have all apparently remained ineffective.
Within the last few years, the pharmaceutical industry has responded to this difficult problem in an attempt to provide controlled substance drug products possessing anti-abuse features. There are essentially three “classical” technical approaches to imparting abuse resistant properties to controlled substances: 1) through a prodrug, 2) via an intractable matrix formulation technique, and 3) by antagonist incorporation into the product formulation. Each approach has been shown to have significant limitations for universal application to a broad range of products. The intent is to impart anti-abuse properties to a drug product via formulation mechanisms which modulate the physical and/or chemical properties of the drug dosage product. This approach may employ admixtures of various excipients, drug antagonists, or utilize production techniques, and combinations thereof to achieve some level of anti-abuse product feature. To date this approach has been relatively ineffective. For instance, Purdue Pharma recently (May 2008) was subject to a regulatory submission review by a panel of FDA experts regarding New Drug Application 22-272 Reformulated Oxycontin®. Panelists' expressed displeasure about the lack of abuse-prevention data and the “poor scientific rigor” as reported in the Wall Street Journal. Purdue's intention was to prepare a tamper-resistant form of the product employing a polymeric excipient which prevented manipulation to an abusable, injectable form.
In contrast to these formulation techniques, anti-abuse properties may be addressed through the drug substance, also known as the active pharmaceutical ingredient (API). At the API level, the physical and/or chemical properties necessary to impart anti-abuse features to the formulated drug product are introduced while maintaining the desired therapeutic value of the drug substance. Two broad categories to this approach have been utilized: 1) the preparation of prodrugs, and 2) the selection of novel salts of the API which exhibit anti-abuse features.
In regard to the prodrug approach, the most celebrated example is the FDA approved product Vyvanse™. Vyvanse™ is a formulated product for solid oral dose administration and employs a prodrug of amphetamine. The FDA's Orange Book refers to two patents covering this technology; U.S. Pat. No. 7,105,486 and U.S. Pat. No. 7,223,735. The anti-abuse feature of Vyvanse™ arises from the drug substance being released only after ingestion and subsequent hydrolysis by enzymes located in the epithelial cells of the intestine. Attempts to abuse the drug by other means are prevented because of the absence of the enzyme.
In co-pending U.S. patent application Ser. No. 11/805,225 [Bristol, et al.] entitled “Salts of Physiologically Active and Psychoactive Alkaloids and Amines Simultaneously Exhibiting Bioavailability and Abuse Resistance”, incorporated herein in its entirety, a number of “classical” formulation and prodrug approaches are referenced which allegedly impart anti-abuse properties to drug substances and to drug products. However, Bristol teaches how the careful selection of organic acid addition salts of amine-containing controlled substances can be prepared which exhibit anti-abuse properties; one factor of several for this desired feature results from the salt's lack of solubility in the mucosal membranes of humans (or animals). In contrast, the salts when subjected to the gastrointestinal tract were transformed and bio-available. The co-pending application describes a platform approach to introducing anti-abuse properties to controlled substances.
Further, in co-pending U.S. patent application Ser. No. 11/928,592 [King, et al.] entitled “Drug Release Properties of Polymorphic Pharmaceutical Substances”, incorporated herein in its entirety, the dissolution profiles associated with various organic acid salts of amine-containing controlled substances is disclosed. In conjunction with the salts lacking solubility in the mucosal membranes, the in vitro dissolution testing of these salts indicated polymorphic behaviors suitable for controlled and targeted release. Consequently, the selection of an organic acid addition salt and of a particular polymorph associated with that salt, provide a means to impart substantial anti-abuse properties into controlled substance drug products.
Drug abuse, in particular controlled substance abuse, is a difficult problem to curtail. There are behavioral aspects to the abuse which may not surrender to any reasonably available solution. For instance, an individual's choice to deliberately swallow multiple doses of a legitimately prescribed oral dosage is nearly impossible to control. The controlled release product approach has had limited effect in mitigating this occurrence. Alternatively, there are proposed product formulations which contain low amounts of an emetic such that when used in the intended dosing regimen the individual is unaffected by the emetic. However, with an intentional oral overdose, the cumulative amounts of emetic from multiple doses results in emesis (and supposedly the extirpation by vomiting of the controlled substance). Consequently, drug abuse while retaining the definition employed above, may also be considered that activity wherein the controlled substance is employed in a route of administration other than by which the product was designed or intended.
It is clear that administrative efforts and chemical technologies will be needed and employed in combination to impede the practice of drug abuse. In co-pending U.S. patent application Ser. No. 11/973,252 filed on Oct. 5, 2007[King et al.], incorporated herein by reference in its entirety, a process is disclosed which employs anti-abuse properties of selected organic acid salts of amine-containing controlled substances and which provides track and trace capabilities through computer databases. The invention provides enablement to the FDA's initiative to develop a new guidance for a similar to, but the chemically comparable topic of, anti-counterfeiting. The FDA's proposed guidance, entitled “Incorporation of Physical-Chemical Identifiers (PCID) into Solid Oral Dosage Form Drug Products for Anti-counterfeiting” is also applicable to the cradle-to-grave administrative monitoring of controlled substances. Indeed, California has instituted such a tracking requirement pursuant to Cal. Bus. & Prof. Code §4034(d), and stating a “pedigree shall track each dangerous drug at the smallest package or immediate container distributed by the manufacturer, received and distributed by the wholesaler, and received by the pharmacy or another person furnishing, administering, or dispensing the dangerous drug”. Also, in a news report found in Generics Bulletin, 2 May 2008 page 7 entitled, “US Aims for Federal Track-and-Trace Route”, legislation has been proposed (HR5839 Safeguarding America's Pharmaceuticals Act) which “will require pedigrees on all prescription medicines sold in the US”. The Act, if enacted, “will require manufacturers, distributors and pharmacies to put in place systems and technologies that will electronically track and trace individual prescription medicines”.
European Patent Application 137600[Stuart et al.; filed Jul. 19, 1984; now withdrawn], which is incorporated herein by reference, entitled “Pharmaceutically Active Salts of Morphine” asserts the preparation of morphine pamoate salts as the mono-morphine salt and the dimorphine salt trihydrate. The authors further performed pharmacological tests in rats and humans to compare the effect of morphine pamoate versus morphine sulfate (human tests) or morphine hydrochloride (rats). Within the context of the application, morphine pamoate employed in the pharmacological testing was dimorphine pamoate trihydrate, the preparation of which was described in applicants' Example 1. In addition, a reference was cited during the initial examination of the application to “morphine pamoate” found in the article “Relationship Between In Vitro Dissolution Rates and Solubilities of Numerous Compounds Representative of Various Chemical Species” published in the Journal of Pharmaceutical Sciences, Volume 54, No. 11, November 1965, pp. 1651-53. Incidentally, in this article, no reference was made to the type of morphine pamoate salt evaluated (mono- or di-morphine salt, or of any polymorphic considerations).
In U.S. Pat. No. 7,201,920 B2 [Kumar et al.], entitled “Method and Composition for Deterring Abuse of Opioid Containing Dosage Forms” the inventors disclose a formulation containing an analgesic and a gel forming polyethylene oxide component and is incorporated herein in its entirety. The matrix resulting from this and other non-active ingredients (excipients) is intended to result in an abuse resistant formulation.
In U.S. Pat. No. 7,153,966 B2 [Casner et al.], the disclosure of which is incorporated herein in its entirety, a process is identified for the preparation of oxycodone possessing very low impurities of 14-hydroxycodeinone. Similarly, in US Patent Application Publication US 2006/0173029 A1 [Chapman et al.], the disclosure of which is incorporated herein in its entirety, a method is disclosed for preparing oxycodone hydrochloride having less than 25 ppm of 14-hydroxycodeinone.
The control of impurity levels in medicinal opiates continues to receive significant inventive attention due to the oversight the US Food and Drug Administration applies to impurities during the drug approval process. US Patent Application Publication US 2008/0132703 A1 [Cox et al.] describes a process for reducing impurities in oxycodone base. In U.S. Pat. No. 6,589,960 B2[Harclerode et al.] the inventors assert the preparation of hydromorphone and hydrocodone compositions having novel impurity profiles. Similarly, in United States Patent Application Publication US 2007/0293676 A1 [Antoninin] describes a method for the separation and purification of hydrocodone by preparative chrbmatography. A process for the purification of levorphanol, a morphinan, is described in United States Patent Application Publication US 2008/0146805 A1 [Haar et al.] And in U.S. Pat. No. 5,981,751 [Mudryk et al.], the inventors describe a process for the removal of residual organic solvents from various opiate based compounds.
In addition to the impurities contained within a given medicinal product, the FDA scrutinizes the polymorphic content of a drug substance and drug product before market approval is granted. Perhaps as a consequence of this scrutiny, a series of relevant United States Patent Application Publications describe various opiate polymorphs, principally those polymorphs observed as the mineral acid salt. United States Patent Application Publication US 2007/0197572 A1 [Calderon et al.] describes nine novel polymorphic forms of oxycodone hydrochloride. United States Patent Application Publication US 2006/0235039 A1 [Lorimer et al.] describes four novel polymorphic forms of hydromorphone hydrochloride. United States Patent Application Publication US 2007/0072889 A1 [Hagen et al.] describes ten novel forms of hydrocodone bitartrate
Related to the assessment of the polymorphic content of drug substances, the preparation, characterization and utility of pharmaceutical co-crystals is emerging as a new approach to imparting unique physical and chemical properties to drug substances. In an article, “Diversity in Single- and Multiple-Component Crystals; The Search for and Prevalence of Polymorphs and Cocrystals, published in Crystal Growth & Design, Volume 7, Number 6, 2007, pp. 1007-1026, the author, G. Patrick Stahly, provides an excellent overview of techniques used in polymorph and co-crystal screening. The investigation of cocrystals is well exemplified in United States Patent Application Publication US 2008/016772 A1 [Zaworotko et al.] wherein the solid-sate synthesis of imides and imines using cocrystals is described.
In a Mar. 29, 2005 report by Dr. William K. Schmidt of Renovis, Inc. the author provides an excellent summation of the approaches employed to impart abuse resistance to controlled substances. This often cited report can be found at http://www.thci.org/opioid/mar05docs/schmidt.pdf or at http://www.thci.org/opioid/documents/schmidt.pdf. Four approach categories were identified along with the companies pursuing a technical implementation strategy for that approach. These four categories and the associated companies are listed below. Additional companies have been added to the original Schmidt report to represent the current contributions and understandings within the industry.
Category 1 Approach: Modified release to resist crushing/extraction Companies: Collegium, Pain Therapeutics (Durect and King Pharmaceuticals), Roxane (Boehringer Ingelheim), TheraQuest, Acura Pharmaceuticals, Intellipharmaceutics Corporation
Category 2 Approach: Prodrugs Company: New River Pharmaceuticals (purchased by Shire Pharmaceuticals)
Category 3 Approach: Agonist and antagonist combinations Companies: Elite, Endo, Purdue Pharma (Euro-Celtique), and 3M
Category 4 Approach: Nasal gel Company: Ionex Pharmaceuticals (purchased by Vernalis)
With the exception of the prodrug approach, the remaining three categories rely upon a formulation technique to impart anti-abuse features to the drug product and consequently, the four categories cited are essentially equivalent to the three classical approaches described in the Background of the Invention. Therefore, to fully recognize the scope and benefit of the present invention it is useful to contrast and compare the prior art generated by the above listed companies to the inventive disclosure herein.
For clarification, each category above is described briefly for the benefit of those unfamiliar with the techniques used by persons abusing drug products. First, the GAO report cited herein describes the crushing/extraction mechanism used by people intent on abusing drugs. Crushing the final dose product can allow for the “liberation” of the controlled substance and defeat any controlled release benefit the formulated drug product may have provided. Without the controlled release property, the full effect of the active ingredient may be felt by the abuser. Similarly, dissolving the formulated drug product in an appropriate solvent and isolating the active ingredient allows for the anti-abuse property to be circumvented. Hence, methods which defeat crushing or extraction impart an anti-abuse property to the drug product.
Indeed, formulation techniques in conjunction with final dose manufacturing technologies have been the mainstay for the production of anti-abuse opioid containing drug products. The approach was to employ ingredients and coatings technologies to modify the behavior of the opioid API, usually available as it's highly water soluble, mineral acid salt or as its small organic acid salt yielding similar solubility properties. Such approaches to anti-abuse formulations are well documented in U.S. Pat. No. 6,103,261 [Chasin et al.] assigned to Purdue Pharma and entitled “Opioid Formulations Having Extended Controlled Release”, the disclosure of which is incorporated herein in its entirety. The literature cited within the '261 patent also provides a significant foundation to the formulation approach to extended and controlled release formulations. The inventors claim a solid oral dosage form of an analgesic compound contained in a controlled release matrix and assert its kinetic release as a function of pH and time as measured by a specific method. In a similar vein, U.S. Pat. No. 6,245,357 B1 [Edgren et al.], incorporated herein by reference in its entirety, describes a sustained release dosage form comprising a drug surrounded by an interior and an exterior wall with an exit for administering the drug to a patient. The pH independent release of drug products consistent with the compartmentalization principles of medicinal chemistry led to U.S. Pat. No. 6,150,410 [Eng et al.] entitled “pH Independent Extended Release Pharmaceutical Formulation”, the disclosure of which is incorporated herein by reference in its entirety, wherein water swellable and acid-soluble polymers in conjunction with pre-tablet granulation methodologies provide unit dosage forms with the titled properties. Besides controlling the extraction and/or release properties of the drug substance from a dosage form by employing extended release properties, dose dumping has also been addressed using formulation techniques. For purposes herein, dose dumping is defined as the, intentional or unintentional, ethanol accelerated phenomenon in which the active pharmaceutical ingredient may be more rapidly released from the dosage form than intended and thereby creating a safety risk and/or the enablement of drug abuse. US Patent Application Publication 2007/0212414 A1 [Baichal et al.] entitled “Ethanol Resistant Sustained Release Formulations”, describes sustained release delivery systems employing hetero- and homo-polysaccharide gums, said systems inhibiting dose dumping of a selected opioid. Finally, in relation to formulation and manufacturing technologies, U.S. Pat. No. 6,419,960 [Krishnamurthy et al.] entitled “Controlled Release Formulation Having Rapid Onset and Rapid Decline of Effective Plasma Drug Concentrations”, the disclosure of which is incorporated herein in its entirety, describes a formulation simultaneously exhibiting immediate release and controlled release properties and employing enteric coating manufacturing technology to achieve same.
In regard to the prodrug approach, release is dependent on biochemical in situ enzymatic cleavage of a covalently bound protecting group or in general, an enzymatic transformation of the prodrug is required in order to produce the pharmaceutically active compound (or subsequently, a metabolite) that exhibits the desired biological activity. The prodrug concept as an anti-abuse mechanism is predicated on the belief that the “protected” pharmaceutical active ingredient is otherwise unavailable for abuse (i.e. in vitro manipulation to yield the active ingredient). The in vivo results from prodrug approaches demonstrate limitations as well. For instance the drug product, Vyvanse™, containing the prodrug lisdexamphetamine dimesylate, exhibits incomplete in vivo removal of the protecting group as indicated by lisdexamphetamine found in the urine, as reported in the FDA's Drug Approval Package, Clinical Pharmacology assessment for Vyvanse™ found at the following website: (http://www.fda.gov.cder/foi/nda/2007/021977s000TOC.htm).
The agonist/antagonist approach is constructed around the ability to sequester an antagonist within an agonist product formulation. In the event that the product formulation is employed in a manner inconsistent with it's intended route of administration, the antagonist is released defeating the anticipated effect from the agonist. With the nasal gel listed in Schmidt's report, the analgesic buprenorphine is formulated for fast effective delivery of the opioid so an anti-abuse product feature is absent perhaps explaining the observation that only sublingual product presentations have been approved in the US in conjunction with Vernalis' partner, Reckitt Benckiser.
In regard to Collegium's effort to impart anti-abuse properties to controlled substances, an abuse-deterrent pharmaceutical composition is described in United States Patent Application Publication Number US 2004/0052731 A1 [Hirsh et al.], the disclosure of which is incorporated herein in its entirety. The publication indicates the intention to alter the lipophilicity of an opioid drug substance by complexation with oleophilic metal salts such as zinc stearate. It is suggested that the “likelihood of improper administration of drugs, especially drugs such as opioids” would be due to the increase in lipophilicity imparted to the opioid by the complexation.
Another version of the modified release approach to resist crushing/extraction and to impart abuse deterrence to a drug formulation is summarized in the following information found on Durect's web site:
“The ORADUR Technology is the basis of Remoxy, a novel long-acting oral formulation of the opioid oxycodone which is targeted to decrease the potential for oxycodone abuse. In December 2007, Remoxy successfully completed a pivotal Phase III study. Pain Therapeutics has stated that it anticipates filing the NDA for Remoxy in the second quarter of 2008. We also have a second ORADUR abuse-resistant opioid product in the Pain Therapeutics alliance, about which Pain Therapeutics has announced positive results from a Phase I clinical trial.”
Durect is the assignee of U.S. Pat. No. 7,074,803 B2 [Litmanovitz et al.], the disclosure of which incorporated herein in its entirety. The inventors describe a means of preparing high concentration opioid formulations suitable for use in gel caps. Interestingly, Pain Therapeutics (mentioned on Durect's website), is the assignee for U.S. Pat. No. 6,765,010, the disclosure of which is incorporated herein in its entirety, describes the use of opioid receptor antagonists in the formulation of tramadol to enhance the analgesic potency of tramadol while mitigating undesired side effects.
Further formulation techniques included those described in United States Patent Application Publication 2003/0118641 A1 [Maloney et al.], which describes a method of combining a therapeutically effective amount of the opioid compound, or a salt thereof, with a matrix-forming polymer and an ionic exchange resin. The inventors assert this combination reduces the abuse potential employing extraction techniques of an oral dosage form of an opioid.
The following information was obtained from TheraQuest's website, http://www.theraquestinc.com/pain/abuse.htm, however no related patents or published patent applications have been identified. TheraQuest describes another formulation technique to impart anti-abuse properties to drug products. Stated therein is:
“TheraQuest's Abuse Deterrent SECUREL™ Technology
Toxicity from high blood levels of sustained release opioids and other abusable drugs often occurs when recreational drug users and addicts crush the contents of the tablet or capsule and ingest the drug orally, snort it or inject it intravenously, after extraction and filtration.
TheraQuest has developed a proprietary secure-release (SECUREL™) abuse deterrent sustained release oral drug delivery platform. SECUREL™ operates by resisting crushing, melting and both chemical and physical attempts to extract the abusable drug. SECUREL™ formulations are difficult to tamper with and are designed to form a viscous substance upon contact with a solvent, such that the abusable drug cannot be easily filtered or drawn into a syringe for intravenous drug abuse. They are also resistant to extraction with common solvents, including alcohol. A potential advantage of such a “passive” abuse deterrent system is that it may protect both medical and non-medical users of opioids and other abusable drugs from intentional or unintentional opioid toxicity, without unnecessary harm to either group from the abuse deterrent technology.”
In U.S. Pat. No. 7,201,920 B2 [Kumar et al.] assigned to Acura Pharmaceuticals, the disclosure of which is incorporated herein in its entirety, the inventors describe a formulation technique to prepare abuse deterrent dosage forms of opioid analgesics by employing a polyethylene oxide polymer to form a matrix.
In March 2008, Intellipharmaceutics reported the successful completion of a pilot clinical trial for its abuse and alcohol resistant sustained release oxycodone. From their website, www.intellipharmaceuitcs.com, the company reports as excerpted below:
“Mar. 27, 2008—IntelliPharmaCeutics Ltd. (Delaware) is pleased to announce significant results from a recently completed pilot clinical trial for its new abuse-resistant, alcohol-resistant once-a-day oral oxycodone formulation by its operating company IntelliPharmaCeutics Corp. of Toronto (“IntelliPharmaCeutics” or the “Company”). The product is covered by pending patent applications for its novel ReXista™ abuse and alcohol resistant drug delivery technology. It is one of the Company's line of in-house analgesic products in development for the management of moderate to severe chronic and acute pain.
The ReXista™ oxycodone product is a novel dosage form, designed to be resistant to abuse by oral ingestion when crushed or chewed, by injection when combined with solvents, and by nasal application when crushed or powdered. The abuse of this important pain relief drug has been well documented over many years.”
Intellipharmaceutics' technology describing the proclaimed attributes through formulation is contained in a series of United States patents, specifically, U.S. Pat. No. 6,676,966 B1 [Odidi et al.], U.S. Pat. No. 6,652,882 B1 [Odidi et al.] and U.S. Pat. No. 6,800,668 B1 [Odidi et al.], each incorporated herein in their entirety.
With respect to the prodrug approach to attaining an anti-abuse formulation, New River's efforts at obtaining FDA approval of Vyvanse™ was well rewarded by Shire Pharmaceutical's purchase of New River for $2.6 billion. New River's U.S. Pat. No. 7,105,486 B2 (Mickle et al.) the disclosure of which is totally incorporated herein by reference, describes the covalent attachment of L-lysine to the drug substance, amphetamine, to provide compounds and compositions exhibiting abuse-resistant properties and useful for the treatment of disorders including attention deficit hyperactivity disorder (ADHD), attention deficit disorder (ADD), narcolepsy and obesity.
Similarly, Buchwald, et al. in United States Patent Application Publication (US 2004/0058946 A1), the disclosure of which is totally incorporated herein by reference, identifies modified oxycodone derivatives (prodrug) such that its physiological activity is only observed after the prodrug is converted to the drug in the mammalian gastrointestinal tract. Mickle, et al. in United States Patent Application Publication (US 2005/0266070 A1), the disclosure of which is totally incorporated herein by reference, identifies hydrocodone conjugates that release the drug substance following oral administration yet are resistant to intravenous or intranasal abuse.
Category 3 of Schmidt's report describes the industry's efforts to formulate opioid drug products which also contain an antagonist. The formulation techniques essentially sequester the antagonist so that the drug product produces the desired pharmaceutical effect when used for its intended purpose. However, should the drug product dosage presentation undergo manipulation (i.e. crushing or extraction) the antagonist is released and the potential for drug abuse is thwarted. Several companies have pursued this approach. For example, successful clinical trials were announced by the company Alpharma and reported in FDAnews Drug Pipeline Alert™ (Volume 4, No. 193, Oct. 3, 2006). The capsule formulation consists of an extended-release opioid with a sequestered core of naltrexone, an opioid antagonist. The sequestering subunit enabling this technology is described by Boehm in United States Patent Application Publication US 2004/01341552 A1, and is totally incorporated herein by reference.
Similarly, Elite Pharmaceuticals is reportedly initiating a Phase II clinical trial of its abuse resistant pain drug also employing the antagonist naltrexone hydrochloride. The report found in FDAnews Drug Pipeline Alert™ (Volume 4, No. 179, Sep. 13, 2006) states the previous Phase 1 trial confirmed the technical approach such that when the drug product was taken as intended, no antagonist was measured in the blood stream. However, if the drug product was crushed, the antagonist was released into the blood stream and the euphoria normally experience by oxycodone hydrochloride abusers was reduced.
Not surprisingly, Purdue Pharma (Euro-Celtique) has also pursued the agonist/antagonist combination formulation in an effort to impart anti-abuse properties to opioid analgesics. In U.S. Pat. No. 7,332,182 B2 [Sackler], the disclosure of which is incorporated herein in its entirety, the inventor includes an irritant in the agonist/antagonist opioid formulation to further discourage use of the drug product for reasons other than its intended purpose. U.S. Pat. No. 6,696,066 [Kaiko et al.], the disclosure of which is incorporated herein in its entirety, describes a sustained release agonist/antagonist formulation capable of producing a mildly negative, “aversive” experience in physically dependent addicts.
Lastly, in regard to the agonist/antagonist approach to abuse resistant products, 3M received U.S. Pat. No. 7,182,955 B2 [Hart et al.], the disclosure of which is incorporated herein, in its entirety, the inventors describe an abuse resistant transdermal dosage form (a patch) formulated and assembled to deliver the desired active agent when the product is used in a manner consistent with its intended purpose yet deliver the antagonist if improperly used.
For the Category 4 approach of the Schmidt report regarding use of a nasal gel, Ionix Pharmaceuticals is the assignee of United States Patent Application Publication 2007/0231269 [Birch et al.] describing the nasal delivery of an opioid analgesic or a non-steroidal anti-inflammatory drug in a manner to produce a therapeutic plasma concentration within thirty minutes with a duration of at least two hours.
Despite the administrative efforts to curtail drug abuse via educational materials, medical professional training, patient counseling, law enforcement support, drug abuse treatment programs, drug prescribing protocols, legislative action, public awareness, governmental reporting, medical professional organizations' support of anti-abuse products, and charitable and religious group influence, and all combinations of these and other activities, the statistics indicate drug abuse is growing at a rate faster than the population's growth. It is clear society has recognized and is aware of the consequences of drug abuse and while administrative measures may diminish the problem, the financial gain available to practitioners of the illicit drug trade likely draw an analogy to the government's attempt at alcohol prohibition and enactment of the Eighteenth Amendment. This legislative exercise proved futile and made many willing participants of the illegal trafficking of alcohol wealthy. Ultimately, the Twenty-First Amendment repealed the Volstead Act and Prohibition ended. With its end, the financial incentive was also removed and alcohol taxation returned. Administrative efforts may have little impact on the drug abuse crisis to which the Nation suffers until our borders are secured.
In respect to the technical efforts expended to curtail drug abuse, industry icons and small companies alike have instituted research and development programs at immense expense to identify reliable solutions, through chemistry, to achieve abuse resistant/tamper-proof drug products. Unfortunately, the rational approaches to date have met with limited success and the alternatives require a more extensive and inventive manipulation of the related chemistries—particularly to impart such properties to the opioid family of drug products. Described herein below is such an inventive solution to address the need for a platform approach to introducing anti-abuse properties to controlled substance pharmaceuticals and to other medicinal products which may be abused.
As in the above discussion, administrative and technical measures will be required to effectively curb drug abuse. The technical contributions have primarily centered upon formulation technologies to prevent the physical extraction of the active ingredient from the dosage product. While the formulation approach is valid, it also contains inherent flaws since any pharmaceutical composition relying on physical mixtures and/or the mixture's differential solubilities and/or other physical/mechanical barriers (e.g. a matrix) to impart anti-abuse properties can be overcome employing physical means. Fundamentally, these various formulation techniques would provide excellent second-line defense mechanisms when coupled with a chemical methodology to impart anti-abuse properties to the drug product. By way of example, with the aforementioned prodrug discussion regarding the amphetamine exemplar embodied in New River's Vyvanse™, the drug product delivers an anti-abuse feature through chemical means which would be very difficult to defeat—and only through chemical transformation. Unfortunately, the prodrug approach, in general, requires significant R&D resources to tailor each prodrug to a host of regulatory specifications before market approval can be granted by the FDA. Consequently, the prodrug approach is costly, time-intensive and does not provide a universal, platform solution to imparting anti-abuse properties to the medially necessary amine-containing controlled substances. The invention described herein encompasses a platform approach to imparting anti-abuse properties at the molecular level through unique salt forms of the opioid alkaloids.
In spite of the ongoing, and extensive, efforts there is still and strong, even mandated, desire for an opioid which is less susceptible to purposeful or incidental abuse particularly with regards to dose dumping.